Krabbe's globoid cell leukodystrophy: deficiency of glactocerebrosidase in serum, leukocytes, and fibroblasts.

The activity of galactocerebroside beta-galactosidase was extremely low in serum, leukocytes, and cultured fibroblasts of patients with Krabbe's disease. Antemortem diagnosis is possible without organ biopsies. The parents of patients showed enzyme activities generally lower than that of normal controls. This finding provides supportive evidence that the deficient activity of galactocerebroside beta-galactosidase is the genetically determined enzymatic defect underlying the disease. Demonstration of this deficiency requires the use of the specific substrate, galactocerebroside. Assays carried out with synthetic, unnatural substrates, such as 4-methylumbelliferyl beta-galactoside, do not distinguish patients or heterozygous carriers from normal individuals.